1. Field of the Invention
The present invention relates to a method for producing an organic light-emitting device.
2. Description of the Related Art
Organic light-emitting devices, which are self-emitting devices, have recently attracted attention for application to flat panel displays, and such devices have been actively developed.
A technology relating to protective films that serve to shield from moisture and oxygen that can penetrate from outside has been studied with the object of improving light emission characteristics of organic light-emitting devices. A transparent insulating film, such as a silicon nitride film and silicon oxynitride film, can be formed as a protective film on a wide area over and on the periphery of an organic light-emitting element, which is a constituent component of an organic light-emitting device.
An external circuit such as a flexible printed circuit board (referred to hereinbelow as FPC) is electrically connected to external connection terminals of an organic light-emitting device in order to transmit display signals to the organic light-emitting device. In this case, sufficient electric connection cannot be obtained unless the protective film that is an insulating film is removed from the external connection terminals. Accordingly, a method is used by which when a protective film is formed by plasma CVD or the like, the external connection terminals are covered with a metal mask or the like to prevent the formation of the protective film on the external connection terminals.
Japanese Patent Laid-Open No. 2002-151254 discloses the four following methods that prevent the formation of a protective film on external connection terminals. With the first method, the surface of external connection terminals is depolarized before the protective film is formed. With this method, the protective film is not formed on the depolarized terminal surface, and the external connection terminals and terminal electrodes of a FPC or the like can be electrically connected by performing UV or ozone treatment of the terminal surface prior to subsequent connection to the FPC or the like. With the second method, a masking tape is pasted on external connection terminals by a method other than a metal masking method, a protective film is formed, and then the masking tape is peeled off, thereby removing the protective film together with the masking tape. With the third method, the surface of external connection terminals is covered with a thin film corresponding to an organic compound layer constituting the organic light-emitting element or a material for covering anode end portions, and photoetching is then performed using a metal mask, thereby removing the protective film together with the thin film or cover material. With the fourth method, a thin film with low adhesion to external connection terminals is provided on the surface of external connection terminals, a protective film is thereafter formed, and the protective film is then peeled off by using a tape.
Japanese Patent Laid-Open No. 2004-165068 discloses a method by which a laser removable layer is formed on a region including external connection terminals, a protective film is formed thereupon, and then laser irradiation is performed to remove the protective film together with the laser removable layer.
External connection terminals are typically provided in a range with a width of equal to or less than 5 mm along a substrate side. Therefore, in a case where a plurality of panels are produced from a large substrate a stripe-like pattern having shielding portions with a pitch of external connection terminals or a grid-like pattern in which shielding portions are provided on external connection terminals and between the panels, can be considered as a mask for use in formation of a protective film. With both pattern masks, openings are much larger than the shielding portion. Therefore, the masks have a low strength and can be easily deformed. As a result, the external connection terminals are difficult to cover reliably and the protective film can wrap around the external connection terminals and adhere thereto, thereby creating electric resistance during external circuit connection. Where the shielding portions are increased in size to impart strength to the mask, the panel frame can become wide and distance between the panels can increase, thereby decreasing the number of panels that can be produced from one substrate.
A method by which a protective film is peeled off by using a masking tape as described in Japanese Patent Laid-Open No. 2002-151254 is used for obtaining a large number of substrates from a large substrate. However, this method may require a process of pasting a masking tape before the protective film is formed, and a process of peeling the tape off after the protective film has been formed. Thus, the number of processes to be performed is increased. In all other methods disclosed in Japanese Patent Laid-Open No. 2002-151254, additional processes may also be necessary to remove the protective film. Thus, the process time required to produce an organic light-emitting device may be extended, productivity can be decreased, and production cost may be raised.